Notes:
The polymerization of styrene oxide by nitronium tetrafluoroborate in nitromethane and methylene chloride at 5, 20, and 50°C is investigated. GPC analyses of the products combined with isocyanate method show that both cyclic and linear oligomers are formed. In CH3NO2 the cyclic dimer and trimer are 2-benzyl-4-phenyl-1,3-dioxolane and 1,3,5-tribenzyl-trioxane, respectively. In CH2Cl2 2,5-diphenyldioxane is isolated. In nitromethane, mainly isomerized structures with acetal linkage are produced, while in methylene chloride isomerization does not proceed. By NMR and IR spectra the presence of C=O and OH end groups in the linear oligomers is shown. There are indications that oligomers are formed both directly from the monomer and by degradation of the polymer.

Notes:
Previous nuclear magnetic resonance measurements on a polymethylsiloxane gum (MW = 75,000) had been interpreted to indicate the presence of considerable segmental motion in both the amorphous and crystalline components at temperatures above the glass temperature. Further investigation again showed the NMR line to be completely narrowed just above the glass point indicating such motions must extend into the crystalline component. This work was extended by the measurement of NMR absorption line widths for temperatures of 80-300°K. on samples of the same gum subjected to gradually-increased crosslinking by electron doses of 3-600 × 106 rep. Here, no change in the NMR properties of low temperature, rigid states were observed, but the room temperature line width progressively increased from 0.019 gauss to over 0.100 gauss peak-to-peak due to the increase in bulk viscosity of the liquid. The “first-order” activation energy associated with the temperature-dependent line narrowing decreased from 10 to 2 kcal./mole. The NMR data indicate that the primary effects of radiation-induced crosslinking are to reduce the chain rotational energy by the creation of defects and to increase the short-range viscosity by the lowering of translational freedom.

Notes:
In the light of special applications, trials were carried out on the separation of steel tubes using commercially obtainable explosive cutting charges in an annular configuration in order to find out their cutting performance and the effects on the environment incurred during separation. Tubes made of St37 steel having a diameter of 220 mm and a wall thickness of 10 mm as well as tubes consisting of hightensile 15 Mo 3 steel with a diameter of 273 mm and a wall thickness of 12.5 mm were used for this purpose. It was possible to cut the tubes accurately and neatly with the charges used. However, the projectiles formed during the detonation process are not compact, for which reason the cutting performance of the commercial charges used is not optimal. There is here a considerable potential for improvement. Measurements of the environmental effects conducted during the trials (fragmentation, blast wave, projectile impact on tube line) show that the incidental effects of explosive tube cutting are controllable.

Notes:
Crystals of amylose were prepared by precipitation from aqueous solution with n-butanol. The crystals are rectangular platelets, and crosses or rosettes formed by the intergrowth of single platelets. In the electron microscope they are seen to consist of layers 75 A. in thickness. Distinct spiral terrace growths related to screw dislocations were not observed, but the presence of dislocation edges suggests that the crystals thicken by a dislocation mechanism. Low-angle, x-ray measurements on aggregates of the crystals reveal a long spacing in good agreement with that calculated from shadow lengths. However, in contrast with other polymers, the long spacing appears to be invariant with crystallization temperature. Electron diffraction spot patterns show that the platelets are single crystals and indicate that the chain molecules are folded within the lamellae.